- •History of Biophysics
- •Viruses possess only a portion of the ______________ of organisms.
- •Characteristics of Atmospheric Turbulence
- •In adult insects, the wings are solid ______________ the veins.
- •Complexities of Animal Energetics
- •Plants and Plant Communities
- •Nature and Subject of Biophysics
- •Molecular Structure of Biological Systems Part 1
- •Molecular Structure of Biological Systems Part 2
- •Energy transfer by charge carriers
- •In effect, selection is operating to prevent change away from this middle range of ______________.
- •Photosynthesis as Process of Energy Transfer and Energy Transformation
- •Thermodynamic Probability and Entropy
- •In atp the reactive group ______________ to the end of the amp phosphate group is not another nucleotide but rather a chain of two additional phosphate groups.
- •The Information Content of a Nucleic Acid
- •Biological Structures: General Aspects
- •Thermal Molecular Movement
- •In the pns, both myelinated and unmyelinated axons are bundled together, much like ______________ in a cable, to form nerves.
- •Models, Heterogeneity, and Scale
- •The Water Structure, Effects of Hydration
- •In a human, if the body temperature exceeds the set point of 37°c, sensors in a part of the brain detect this ______________.
- •Water Potential and Water Content
- •Water Potentials in Organisms and their Surroundings
- •Structure Formation of Biomacromolecules
- •Self Assembly and the Molecular Structure of Membranes
- •Mechanical Properties of Biological Membranes
- •Systems, Parameters and State Functions
- •In thermodynamics, systems are classified as follows according to the nature of their boundary against their environment:
- •Potential Energy Contour Tracing
- •Entropy and Stability
- •Pauli Exclusion Principle
- •Строение атомов и принцип Паули
- •Electronegativity and Strong Bonds
- •Электроотрицательность
- •Internal Energy
- •Внутренняя энергия
- •Bond Energies
- •Энергия связи
- •Water, Acids, Bases and Aqueous Reactions
- •Стохастические модели взаимодействия
- •Рентгеноструктурный анализ
- •Nuclear Magnetic Resonance
- •Ядерный магнитный резонанс
- •Scanning Tunnelling Microscopy
- •Принцип действия сканирующего туннельного микроскопа
- •Patch Clamping
- •Proteins
- •Nucleic acids
- •Дифракция рентгеновских лучей
- •Photo- and chemo-bioenergetics
- •Biological systems
- •If all relevant protein carriers are in use, increases in the ______________ do not increase the transport rate.
- •Neurobiophysics
- •Распространение нервного импульса
- •Nerve Cells
- •Аксон и нервный импульс
- •Myelinated Neurons
- •Signal reception
- •Time-resolved Crystallography
- •Biological Polymers
- •Nucleic Acids
- •Нуклеиновые кислоты
- •Nucleic Acid Conformation: dna
- •Proteins
- •Protein Folding
- •In terrestrial vertebrates, the forebrain plays a far more ______________ in neural processing than it does in fishes.
- •Фолдинг белка
- •Respiration
- •Bacterial Motion
- •Muscular Movement
- •In some neurons specialized for rapid signal conduction, the axon is encased in a myelin ______________ that is interrupted at intervals.
- •Energy Exchange
- •In addition, the interactions that occur between members of a population also depend critically on a population’s size and ______________.
- •Continuity in the Biosphere
- •Water Vapor and Other Gases
- •Газы атмосферы
- •Covalent Bonds, Molecular Orbitals
- •Coordinative Bonds, Metallo-Organic Complexes
- •In dry years, when only large, tough seeds are available, the ______________ beak size increases.
- •Типы металлоорганических соединений
- •Hydrogen Bond
- •Mechanisms of Molecular Energy Transfer
- •In general, the following mechanisms of intermolecular energy transfer must be considered: energy transfer by radiation, energy transfer by inductive resonance, energy transfer by charged carriers
Строение атомов и принцип Паули
Принцип Паули помогает объяснить разнообразные физические явления. Следствием принципа является наличие электронных оболочек в структуре атома, из чего, в свою очередь, следует разнообразие химических элементов и их соединений. Количество электронов в отдельном атоме равно количеству протонов, так как электроны являются фермионами; принцип Паули запрещает им принимать одинаковые квантовые состояния. В итоге, все электроны не могут быть в одном квантовом состоянии с наименьшей энергией (для невозбуждённого атома), а заполняют последовательно квантовые состояния с наименьшей суммарной энергией (при этом не стоит забывать, что электроны неразличимы, и нельзя сказать, в каком именно квантовом состоянии находится данный электрон). Примером может служить невозбуждённый атом лития (Li), у которого два электрона находятся на 1S орбитали (самой низкой по энергии), при этом у них отличаются собственные моменты импульса и третий электрон не может занимать 1S орбиталь, так как будет нарушен запрет Паули. Поэтому, третий электрон занимает 2S орбиталь (следующая, низшая по энергии, орбиталь после 1S).
Electronegativity and Strong Bonds
Although the propensity that a given atomic species displays for losing or gaining electrons is determined by the dual factors of ionization potential and electron affinity, an adequate qualitative measure of the same thing is provided by a single parameter known as the electronegativity, eN. Atoms with large electronegativities tend to capture electrons, whereas the opposite is the case for atoms with small electronegativities (these being said to be electropositive). A reliable scale of electronegativity has been derived by Linus Pauling and it is, as indicated above, a dual measure of ionization energy and electron affinity.
If the difference in the electronegativities of two atoms is quite small, there will be no clear tendency for one to lose an electron while the other gains this subatomic particle. There is thus no basis for ionic binding in such a situation. Instead, one has either covalent bonding or metallic bonding, the first of these occurring if the two atoms are both electronegative, and the latter arising when they are both electropositive. An example of covalent bonding is seen if the two atoms involved are both fluorine. The nine electrons in an atom of this element are arranged in such a way that there are two in the 1s orbital, two in the 2s orbital, two in each of the 2px and 2py orbitals, and finally a single electron in the 2pz orbital. It is only the latter orbital, therefore, which lacks an electron and, as we saw in the case of ionic bonding, it can fulfil this need by acquiring an electron from another atom. However, in the case of the covalent bond, it does this not by completely removing an electron from that other atom, but rather by entering into a mutual sharing of atoms, in which the unfilled orbitals of both atoms are filled by the other's lone 2pz electron.
On the example of a hydrogen fluoride molecule one can see, that the 2pz orbitals alone are involved in the binding. Although the interatomic bond is highly directional, as mentioned earlier, it possesses rotational symmetry and there is very little resistance to rotation of one of the atoms with respect to the other, about the z-axis. This form of covalent bonding is known as a sigma bond and numerous examples are encountered in molecules having biological relevance. In the case of the HF molecule the incomplete orbitals, the 1s of hydrogen and the 2p of fluorine, overlap and the two electrons are shared by a sigma-bond.
Define the following words
Propensity, affinity, to acquire, to derive, to gain, the latter, reliable.
Complete the sentences
Atoms with large electronegativities tend to capture electrons, whereas…
If the difference in the electronegativities of two atoms is quite small,…
A reliable scale of electronegativity…
An example of covalent bonding is seen if…
The nine electrons in an atom of this element are arranged in such a way that…
Although the interatomic bond is highly directional,…
In the case of the HF molecule the incomplete orbitals…
Put the following words and word combinations into the gaps
propensity / electron affinity / capture / unfilled orbitals / rotational symmetry / ionic binding
At room temperature, the even members possess a center of inversion in the central C–C bond while the odd members other than malonic exhibit a two-fold ______________ about the central carbon atom.
______________ is a measure of the energy that is released when an atom acquires an electron.
The ______________ of four hydrogen can form four covalent bonds by a sharing of pairs of electrons between carbon and hydrogen.
In ______________ both nuclei are bound by a charge increase which is localized in the region of a single nucleus.
Electronegativity is the ______________ of an atom or molecule to attract the electronic charge of a covalent bond.
Electron affinity refers to the ability of an element to ______________ electrons.
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